The present invention relates to the field of wireless communication networks. More specifically, the present invention relates to modeling migration of call traffic in multiple mode wireless networks for use in wireless network planning tools.
As wireless communication has become more popular, wireless service providers have felt increasingly pressured to use the wireless radio frequency,(RF) spectrum as efficiently as possible. Greater efficiency allows a service provider to carry more calls using a given amount of RF spectrum. The problem of efficiently assigning the given amount of RF spectrum within a wireless network is a complex one.
Some wireless communication networks have traditionally employed analog technology such as the Advanced Mobile Phone Service (AMPS). AMPS employs frequency modulated transmission on a finite number of thirty kilohertz channels. An ever increasing subscriber base has overloaded the RF spectrum allocated to such analog systems, sometimes leading to blocked calls and decreased quality of service.
As demand for wireless service has grown, wireless carriers have been developing innovative solutions to meet increasing capacity needs. As a result, digital technologies, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Global System for Mobile Communications (GSM), and so forth, are emerging to coexist with and possibly eventually replace the analog technology. Such digital technology results in substantial increases of capacity of the RF spectrum, for example, up to ten times that of analog technology. In addition, digital technology has the potential to mitigate three major problems encountered by users of analog technology, that is, static, loss/interruption of signal when passing between cells, and failure to get a connection because of congestion.
Multiple mode refers to a wireless communication network that employs more than one communication technology. A multiple mode network can be a network that employs a combination of two or more analog and digital technologies or a network that employs only multiple digital technologies. One exemplary multiple mode network is a combined dual mode analog and digital network. Such a dual mode network is typically used when a carrier has an analog technology infrastructure in place and begins a migration, or shift, to a digital technology. An immediate conversion to a digital wireless technology can be very costly. Thus, multiple mode networks, such as the exemplary dual mode analog/digital network, serve as transition networks between an entirely analog network and an entirely digital network. Examples of multiple mode networks include AMPS/CDMA, AMPS/TDMA, TDMA/GSM, AMPS/CDMA/TDMA, and so forth.
Automated approaches to network planning are being developed to assist carriers in efficiently assigning the given amount of RF spectrum, i.e., channels, for wireless networks. Some of these automated network planning tools involve simulating the actual wireless network to predict the propagation of radio frequency (RF) signals in order to define the radio coverage areas for the servers (i.e., closest base stations from a signal propagation viewpoint), to characterize potential interference within a simulated environment in order to effectively make channel assignments, to perform traffic analysis, and so forth.
Generally, traffic analysis is the analysis of traffic density, capacity, and call patterns specifically for system performance improvement. Traffic analysis may be performed by engineers utilizing a network planning tool to determine the number and the kinds of circuits and the quantities of related terminating and switching equipment needed to meet current and anticipated call traffic loads throughout a communication network.
A realistic representation of the radio coverage areas for servers in the simulated wireless network and the call traffic loads, or total traffic carried during a specified time interval by each server, are useful for subsequent related activities such as CDMA planning, frequency assignment, and so forth. Accurate traffic analysis is particularly significant when determining the ability of a multiple mode network to accommodate the migration, or shift, of call traffic from the analog to the digital technology. An accurate model of call traffic migration from, for example, the existing analog infrastructure to an emerging digital technology, is important for evaluating the ability of the digital technology to accommodate the increased call traffic loads, to predict the costs and resource constraints associated with adjusting transmission power, to perform a successful hand down of call traffic from the digital to the analog technology, and so forth.
One prior art network modeling tool performs traffic analysis for only a single technology type, that is, an analog system. In this prior art network modeling tool, if a second technology type is to be modeled, for example, CDMA, the digital call traffic data is distributed over the radio coverage area served by the analog technology with no recognition of the unique characteristics or settings of the digital technology. In particular, this prior art network modeling tool is unable to accommodate the differences between radio coverage areas for each of the analog and digital systems. A radio coverage area for a CDMA server may differ from that of an AMPS server because CDMA is a power-controlled system whose performance is very sensitive to multiple user interference. A CDMA system will try to meet a given objective and ensure that a minimum or required signal level is always met. As such, in an actual environment a radio coverage area for a CDMA server may differ from the radio coverage area for an AMPS server, even when the CDMA and AMPS servers are located at the same cell site.
In a multiple mode network planning tool, an additive distribution of digital technology call traffic over the existing analog technology radio coverage area could create an artificial characteristic for the traffic, give a less accurate estimate of the interference, and cause too dense or too sparse a build up of needed capacity. As a result, there exists a need for a system and method that accurately models call traffic migration from an existing communication technology to an emerging communication technology.
Accordingly, it is an advantage of the present invention that a method and system are provided for modeling a migration of call traffic from a first server to a second server in a multiple mode wireless network.
Another advantage of the present invention is that the system and method accurately model call traffic migration by taking into account the unique characteristics of the technologies utilized in the multiple mode wireless network.
Another advantage of the present invention is that the system and method utilize radio coverage areas that closely depict the actual radio coverage areas of each of the first and second servers so that call traffic loads for overlapping cells may be accurately portrayed.
It is yet another advantage of the present invention that the method and system can rapidly accommodate changes in call traffic loads and migration patterns.
The above and other advantages of the present invention are carried out in one form by a computer-based method for modeling migration of call traffic from a first server to a second server. The first server operates using a first technology type and a second server operates using a second technology type in a multiple mode wireless network. The method calls for generating a first traffic map having a first call traffic load distributed over a first radio coverage area of the first server, and generating a second traffic map having a second call traffic load distributed over a second radio coverage area of the second server. The method further calls for determining a proportion of the first call traffic load to shift from the first server to the second server, and adapting the second traffic map to include the proportion of the first call traffic load.